Channel notify method error handling

[deweerdt]

No description provided.

[kazuho]

Thank you for the PR.

Is this PR based on your observation that we have a code path that reaches this function without the context variable being non-NULL?

[deweerdt]

@kazuho this is the same observation by coverity as for EVP_EncryptInit_ex most of the other cases in the code base check for the error return. If it's impossible in this case -- i don't know about mruby to understand if this can be an issue -- we should close this PR.

[kazuho]

Thank you for the clarification. I'll defer the decision to @i110. I believe that we have other parts of code that depend on mrb_data_check_get_ptr, and that we should have a consistent coding pattern assuming that the type of the object being passed to the caller of the get_ptr function is known to be of the correct type.

[i110]

I guess there's no chance to have this ctx be NULL, but as you know Ruby lets us various magics, so I think we should handle errors in any cases. Then, here we should rather use mrb_data_get_ptr that does that error checks and raises an TypeError in irregular cases. At least, we must not return the error object (it has no effect here)

[i110]

I filed #1794, so close this. @deweerdt Thank you for finding the issue!

[i110]

done